Re: adding sockets with cube to armor?
Well, you can do that as a Larzuk quest reward. He will add 1 socket to rare/set/unique armor and 1 or 2 (50%/50% chance) to a magic (blue) item, if the item is without sockets. He also can add maximum possible sockets for that item in a white (or white superior) item.
But don't think defence is good in Diablo2 LOD. Actually it's not worth it at all. If you want MF, get a white armor with 4 sockets and socket it with 4 perfect topazes. Ultimate beginner's armor.